A Terminal High Altitude Area Defense (THAAD) interceptor is launched from the Pacific Spaceport Complex Alaska during Flight Test THAAD (FTT)-18 in Kodiak, Alaska, July 11, 2017.Credit: HANDOUT/REUTERS

The U.S. State Department has approved the possible sale of a THAAD anti-missile defense system to Saudi Arabia at an estimated cost of $15 billion, the Pentagon said on Friday in a statement citing Iran among regional threats.

Saudi Arabia asked to purchase 44 Terminal High Altitude Area Defense (THAAD) launchers and 360 missiles, as well as fire control stations and radars.

"This sale furthers U.S. national security and foreign policy interests, and supports the long-term security of Saudi Arabia and the Gulf region in the face of Iranian and other regional threats," the Pentagon's Defense Security Cooperation agency said in a statement.

Iran has one of the biggest ballistic missile programs in the Middle East, viewing it as an essential precautionary defense against the United States and other adversaries, primarily Gulf Arab states and Israel.